DERIVATIVE INSTRUMENTS 2 (Details) (Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	$ 99,273	$ 82,778
Fair value Derivative Liabilities	140,402	106,800
Commodity Contract [Member] | Derivatives-Energy Related-Current [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	85,368	56,327
Fair value Derivative Liabilities	109,744	77,993
Commodity Contract [Member] | Derivatives-Energy Related-NonCurrent [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	13,905	26,451
Fair value Derivative Liabilities	19,926	22,131
Interest Rate Contract [Member] | Derivatives-Other [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	0	0
Fair value Derivative Liabilities	$ 10,732	$ 6,676